It rains a lot during Qingming Festival. Why does it always rain in Tomb-Sweeping Day?

Tomb-Sweeping Day is a traditional festival in China, and it is also the most important festival for offering sacrifices to ancestors and sweeping graves. Grave-sweeping is commonly known as going to the grave and offering sacrifices to the dead. Most of the Han people and some ethnic minorities visit graves in Tomb-Sweeping Day. According to the old custom, when sweeping graves, people should bring food, wine, fruit, paper money and other items to the cemetery, offer food to their relatives' graves, then incinerate the paper money, cultivate new soil for the graves, fold a few green branches and insert them in the graves, then kowtow and worship, and finally eat food and drink and go home.

I believe everyone has recited such a poem: "It rains a lot during the Qingming Festival, and pedestrians on the road want to break their souls". It often rains before and after Qingming Festival, especially in the south, but Qingming Festival is obviously a cultural festival. Why does it rain? First of all, we should know how the rain came. Water in rivers, lakes and seas evaporates into steam and rises to the sky. The higher it is, the colder it is. These water vapor liquefied into small water droplets in the cold high altitude to form a cloud, and the small water droplets in the cloud collided with each other to become large water droplets, and finally fell down to form rainfall.

then the question is, why does it rain around Qingming? In fact, Qingming is not just a day to sweep graves. As one of the 24 solar terms, Qingming itself represents a meteorological stage that lasts for half a month. China's climate has always been dominated by two forces, one is the cold wind from Siberia, and the other is the warm wind from the Pacific Ocean. Due to the north-south movement of the direct point of the sun, the influence of these two forces is changing.

in spring, the northern hemisphere receives more sunlight. The Pacific warm wind carries a large amount of water vapor to "attack the city slightly", so before and after Qingming, the water vapor in the Pacific warm wind is constantly liquefied by the influence of cold wind and high-altitude low temperature, forming rainfall. Speaking of which, it's probably clear. During the Qingming period, the continuous rain in the south of the Yangtze River was caused by the interaction of cold and warm air currents.